On 10/04/2020 14:23, Bruce Richardson wrote: > On Fri, Apr 10, 2020 at 11:51:56AM +0100, Kevin Traynor wrote: >> On 07/04/2020 17:27, Kevin Traynor wrote: >>> stringop-overflow warns when it sees a possible overflow >>> in a string operation. >>> >>> In the rte_memcpy functions different implementations are >>> used depending on the size. stringop-overflow is raised for >>> the paths in the function where it sees the static size of the >>> src could be overflowed. >>> >>> However, in reality a correct size argument and in some cases >>> dynamic allocation would ensure that this does not happen. >>> >>> Disable this warning at the top level as it is being raised on >>> several components. >>> >>> For example, in the case below for key, the correct path will be >>> chosen in rte_memcpy_generic at runtime based on the size argument >>> but as some paths in the function could lead to a cast to 32 bytes >>> a warning is raised. >>> >>> In function ‘_mm256_storeu_si256’, >>> inlined from ‘rte_memcpy_generic’ >>> at ../lib/librte_eal/common/include/arch/x86/rte_memcpy.h:315:2, >>> inlined from ‘iavf_configure_rss_key’ >>> at ../lib/librte_eal/common/include/arch/x86/rte_memcpy.h:869:10: >>> >>> /usr/lib/gcc/x86_64-redhat-linux/10/include/avxintrin.h:928:8: >>> warning: writing 32 bytes into a region of size 1 [-Wstringop-overflow=] >>> 928 | *__P = __A; >>> | ~~~~~^~~~~ >>> In file included >>> from ../drivers/net/iavf/../../common/iavf/iavf_prototype.h:10, >>> from ../drivers/net/iavf/iavf.h:9, >>> from ../drivers/net/iavf/iavf_vchnl.c:22: >>> >>> ../drivers/net/iavf/iavf_vchnl.c: >>> In function ‘iavf_configure_rss_key’: >>> >>> ../drivers/net/iavf/../../common/iavf/virtchnl.h:508:5: >>> note: at offset 0 to object ‘key’ with size 1 declared here >>> 508 | u8 key[1]; /* RSS hash key, packed bytes */ >>> | ^~~ >>> >> >> As an alternative, we could remove these warnings for rte_memcpy.h(s) >> only. WDYT? >> >> diff --git a/lib/librte_eal/x86/include/rte_memcpy.h >> b/lib/librte_eal/x86/include/rte_memcpy.h >> index ba44c4a32..862e0c402 100644 >> --- a/lib/librte_eal/x86/include/rte_memcpy.h >> +++ b/lib/librte_eal/x86/include/rte_memcpy.h >> @@ -19,4 +19,6 @@ >> #include <rte_config.h> >> >> +#pragma GCC diagnostic ignored "-Wstringop-overflow" >> + >> #ifdef __cplusplus >> extern "C" { > > Limited disabling is always better than global disabling, so given the > choice of the two, +1 for this. >
Thanks Bruce. The slight disadvantage of this approach in short term is a similar issue may also occur for gcc10 on ARM, but I don't have a setup to test that, so an additional arm/eal fix may be required later. I will limit fixing to what I can test, x86. Gavin, can you check if a similar change is required for gcc10 on ARM? > /Bruce >